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Old 04-13-2015, 12:26 AM
miscrms miscrms is offline
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Default Re-using complete Leaf Drive System (w/VCM)

Updated with progress 12/11/2015


- Identify minimum set of components needed to re-use a Nissan Leaf drivetrain outside a Leaf, retaining basic functionality of charging, driving, and regen braking.
- Transplant the complete drive system from a salvaged Nissan Leaf into a new vehicle.
- Document size, weight, and interoperability requirements of major components to reduce risks to others considering this conversion path.


My intention is to operate the Leaf drive system as closely as possible to how it was originally intended by Nissan. In general this will mean using as much of the Leaf's components as necessary to convince them that they are still in a properly functioning Leaf and operate to as normal. While I am also interested in the possibility of operating individual components independently and/or modifying / enhancing their function, that's not the focus of this particular project for the time being.

3/2015 - Procured "rolling chasis" for eventual conversion, 1973 Saab Sonett III with prior 96V DC conversion. Very light (~1800lbs stock), very low CdA (on par with 1st gen Insight), pretty easy to work on with removable fiberglass body over steel frame/pans.
4/2015 - Completed initial survey of failsafe modes of major systems using the factory service manuals.
5/2015 - Procured a 2012 Nissan Leaf SL from salvage auction, began testing and teardown.
5/2015 - Successfully rewired Leaf HV battery into two symmetrical 1/2 packs.
6/2015 - Demonstrated Leaf operating in torn down state with various combinations of systems omitted.
7/2015 - Completed removal of all major components from Leaf.
11/2015 - Completed successful tabletop demo of Leaf drive system charging, going ready, and into D/N/R.
12/2015 - Documented most harness connectors required for operation.
12/2015 - Documented size, weight of most major components.

At this time, here are the main components I believe are required to get the Leaf Drive System running and charging. Items marked with a (*) must all be from the same vehicle, or will require reprogramming with factory Consult III+ tool. Although the rest of these components could be sourced from different vehicles, junk yards, or even new, getting as much as possible from a single salvaged vehicle is probably the most practical / cost effective strategy for this particular approach given the number of components required. The added benefit too is that I will probably end up using many more parts from the Leaf (Cooling system, HVAC, lighting control, keyless entry, radio, NAV, etc) since its there and already integrated. Additional components beyond whats listed here are likely to be required to get Regenerative Braking operational, but exactly what is unproven at this time.

1. Traction Motor w/ Park Lock Mechanism
2. Inverter
3. DC/DC J/B (Charge relays, DC/DC converter)
4. VCM* (Voltage Control Module, like ECM)
5. BCM* (Body Control Module, mainly for security related functions)
6. Smart Key*
7. Complete Battery Box*
a. LBC* (Lithium Battery Controller, BMS)
b. Battery Modules
c. Battery JB (Main System Relays, Contactors)
d. Battery Low Voltage Harness (LB connectors)
e. Battery HV Disconnect (or interlock defeat, though disconnect strongly recommended)
f. Battery temp sensors x4
g. If not using complete box as is you can omit the box itself, battery heaters, battery heater relay. May need additional HV cabling in place of bus bars if not using original box.
8. ESC (Electronic Shift Control)
9. Shift Selector
10. Power Button
11. NATS Receiver
12. Main (lower) combination meter
13. OBC (On Board Charger)
14. Charge Ports
15. Pedal Box (Brake and Accelerator switches and sensors, if not from same vehicle _may_ need Consult III+ to set brake stroke sensor zero position)
16. IPDM and all fuse/relay boxes
17. 12V Battery
18. All HV Wiring Harnesses (Battery Internal, Battery to DCJB, QC Port to DCJB, OBC to DCJB & Charge Port, Inverter to Motor, Inverter to DCJB, Heater to DCJB (or interlock defeat), AC Comp to DCJB (or interlock defeat).
19. Motor Control LV Harness (Traction motor, Inverter, Park Lock, Heater, QC interlock, DCJB)
20. Motor Room LV Harness (Cooling, Accelerator, Brake, VCM, QC Port, 12V Power/GND)
21. Main LV Harness (Combination Meter, ESC, BCM, Power Switch, NATS Amplifier)
22. Body LV Harness (HV Battery, OBC, BCM)

With these components, the system should initiate and charge from LV1/2 and QC (not tested), should go ready and shift from Park to D/N/R and return to park. Power cycling should work as normal, and though DTCs are reported none should need to be cleared between cycles. In this state, the following DTCs and warnings should be displayed:
Current DTCs:
U1000 CAN Com
U0415 Vehicle Speed (ABS)
B2557 Vehicle Speed (ABS / Comb Meter mismatch)
B2626 Outside 1 Antenna
B2627 Outside 2 Antenna
B2628 Outside 3 Antenna (door key sensors, likely a few more of this type if interior sensors disconnected)
Charger: OK None
P31B3 CAN Error (AC Auto Amp)
P3194 CAN Error (ABS)
P3195 CAN Error (IBU)
U1000 CAN Com
P31B9 CAN Error (Electronic Parking Brake)
P31EE AC Refrigerant Pressure Sensor
P31E8 Water Pump 1
P31EA Water Pump 2
HV Battery: OK
U1000 CAN Com
Motor Control: OK
U1000 CAN Com

Dash shows I-Key error (due to missing door sensors I believe) and T/M System Malfunction (likely multiple causes, probably IBU/ABS mainly) as well as warning lights for PS (power steering not connected), BRAKE (parking brake not connected), traction control/VDC (ABS not connected), ABS, Brakes warning (IBU/pressure sensor), airbag (not connected), EV System warning, headlight warning (not connected)

Regenerative Braking will be studied more once I start putting the system into the new vehicle. The system as it stands now _may_ have pedal off regen, but no other regen as its the IBU that sends braking force requests to the VCM. At a minimum adding regen will require addition of the IBU/master cylinder. It may also require the ABS unit and/or EPS but this is still unclear. Depending on how things work out, my initial build will probably include the IBU, possibly wheel speed sensors, possibly ABS but probably not EPS controller. After testing we'll see where we go from there.

Although not listed above as you can technically operate without it, you will need some means of cooling the HV components (motor, DCJB, Charger, Inverter) either using the stock radiator, fans, and water pumps or something else.

Any HV components not used (example heater, AC Compressor) will require some means of defeating the HV interlock check. The VCM looks for connectivity at all HV connections, and will not let the system be enabled without it.

My working list of component weights and dimensions can be seen here, with dimensioned photos showing more detail beginning on page 8 of this thread.

My working list of harness connectors (referenced to 2012 service manual notation) is here:

My summary of the DTC failsafe conditions from various controllers can be found here:

Youtube videos I've posted related to this project:
Initial Teardown and component locations:

Tabletop demo Pt1 (demonstrating ready, Shift to D/N/R):

Tabletop demo Pt2 (demonstrating charging, fast ready, no DTC clear needed)

Other projects I know of using Leaf drive system in a similar way:

If you have a similar project going let me know, and I'll add a link! Please feel free to share your experiences with the Leaf system on this page and I'll try to incorporate into the summary here as well.


Last edited by miscrms; 12-14-2015 at 01:31 PM.
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Old 04-13-2015, 04:46 PM
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tylerwatts tylerwatts is offline
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Hi Rob. I'm sort of doing this, and not. I have a complete Mitsubishi i-MIEV out of its shell that is going into a new chassis. But it will operate as it always did, thinking it is an i-MIEV. If you can learn to talk the leaf's Canbus language then you can do it no problem. It's the learning and development that are tricky.
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Old 04-14-2015, 12:52 AM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

Thanks TW, best of luck with your project!

My intention in general is not to have to do much in terms CAN, as I'm hoping I can use enough of the Leaf to let the controllers talk to one another as they normally do. At the moment I'm just trying to get a clearer picture of just how much stuff would have to be brought over to accomplish that goal. At some point it could get to where I'd be better off developing a small CAN spoofer to send certain messages than to over complicate the integration in the new vehicle too much Hopefull that will get easier to sort out once i actually get a Leaf, but in the mean time I figure its not such a bad thing to be spending some time getting familiar with the service manual, DTCs and controller locations and functions

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Old 04-14-2015, 01:00 AM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

So I did finally look at the BCM, and its failsafe conditions aren't as bad as I'd feared. They are mostly security related, so as long as you have a BCM, VCM, dongle, LBC and key all from the same donor vehicle it seems like the BCM should be ok to ask the VCM to go ready. Not clear yet if you can use just the NATS amp behind the power button, or if its going to want the keyless entry / start system to be present.

I'll update the table and top post with the details soon.

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Old 04-14-2015, 08:02 AM
dedlast dedlast is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

I am hoping to do the same thing with a Leaf, some day. I still have some other stuff to do first, though.

What got me thinking it could be done was a video I saw. Someone took the elctronics out of a Leaf and tied it all up to a peg board, then made it run. I looked for it a minute ago but it didn't come up in my search. I'll have to look again later.

edit: Found it!


Last edited by dedlast; 04-14-2015 at 08:30 AM.
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Old 04-14-2015, 11:17 AM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

Original post captured before edits / updates:

I've seen cases where some folks are working on re-using individual components from a Nissan Leaf, but am wondering if anyone has done any work on what it would take to use the complete system (battery, bms, motor, inverter, charger) while retaining the VCM controller to talk to these components via CAN? There are certainly some downsides to this approach in terms of flexibility, and likely some challenges to keeping the VCM happy outside a Leaf, but it seems to me the advantages in terms of retaining a fairly robust, proven integration and control system (not to mention not having to reverse engineer the proprietary control scheme) could be substantial.

If anyone has done any tinkering in this realm I'd very much like to hear your thoughts / experiences!

I don't have a Leaf to play with yet (hopefully getting a salvage one in the next few months) so I've started by digging into the factory service manuals for the 2011 MY Leaf to try and get a sense of what the minimum number of components would be to allow the VCM to function fairly normally (ie likely showing DTCs, but no significant reductions in performance / capabilities). In particular there is an interesting table beginning on page EVC-79 which shows the relation of various DTCs to failsafe conditions generated by the VCM. I started by looking at the CAN communication related errors, figuring that this would be the first gate to pass when the VCM comes online. What controllers is it looking for traffic from before it will allow the system to go ready and energize?

That resulted in the following table:

From this first test, it looks like the following would be required at a minimum:

That seems like a pretty manageable list for starters. Digging through the rest of the list, here are some other things that could be issues.

U10** errors: Not sure who generates these? Seems like maybe just each individual controller can generate them if there are general communications problems on the CAN bus, but need to understand better.

BCM - This is a very complicated one. Its sort of the master controller of the non-EV CAN bus, and would bring in lots of potentially nice creature comforts but also complications like security. It appears that the VCM may be able to operate just fine without it, as long as the ready signal is applied with the right voltage / timing on the correct pin? There is a complication in that there are several P16** DTCs that appear to be security related in the VCM that look for communication with the BCM. For example, P1610 says it will put the VCM in "lock mode" preventing it from letting the EV system go ready on request if it has gone ready 5 consecutive times without being able to communicate with the BCM. If trying to operate without the BCM it may be necessary to clear this DTC periodically (if it can be easily cleared) or provide a minimal set of BCM CAN responses to the VCM to prevent these errors.

Contactors - located in the battery box, the VCM wants to see these working as expected. Assume should be used pretty much as is.

IPDM / DCC Conv - Basically the fuse / relay box. Would generally be useful to retain (particularly dc:dc), but of course it has its own CAN controller and expects to be able to talk to the BCM or enters failsafe mode. Without that controller it looks like there might be some work to be done to open and close several relays on related CAN commands. Or it may be possible to get enough of it to work without the CAN controller connected to keep the VCM happy (with dc:dc in constant 14V mode?).

ED-IBU - master cylinder / brake controller, looks like you can go without it but will not be able to use Regenerative Braking if its not present. Its the IBU that sends a brake torque request to the VCM. Would be interesting to see if the brake pressure sensors will be ok with having the hydraulic lines just capped off or if you'd have to either use the Leaf calipers or adapt the leaf master cylinder to the host vehicles calipers? Would presumably need brake pedal sensors / switches if trying to use the IBU.

Throttle sensors - There are two, it looks like the resistance of one it twice that of the other. The two need to be consistent with one another and in the right voltage range to keep the VCM happy.

Cooling System / water pumps - In general seems like a good idea to use the stock liquid cooling system as much as possible, perhaps with the radiator substituted for the host vehicles if its relatively comparable? The VCM does look for a reasonable PWM duty cycle on both water pump drivers.

AC - Looks like it can be done without. Although its driven by the HV system i believe you need the BCM / AV Ctl (or the equivalent CAN messages) to control it.

ABS / Traction / Stability / Steering control - somewhat surprisingly to me at least, looks like the VCM is ok without this present which seems like a good thing for re-use flexibility. May be an issue if trying to use BCM?

Airbag - crash sensor can shut HV system down, but VCM seems ok if its not there.

TCU - telemetry controler, car wings app interface, VCM seems ok without it

Comb meter - Speedo, etc, VCM ok without it, but no ASCD (cruise control)

AV Ctl - controls dash display and buttons I believe, VCM ok without but no charge timer or pre-AC.

That's what I've got so far. You can view the whole spreadsheet that I've been making notes in here:

Again, any thoughts, insights, experiences much appreciated! If there are any significant findings / discussions I'll try to keep this top post updated.


Last edited by miscrms; 04-14-2015 at 11:53 AM.
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Old 04-14-2015, 12:57 PM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

Updated first post to reflect findings on BCM. Doesn't look to tricky to include it which gets around the security related VCM errors, provided that you have a matching VCM, BCM, Security Dongle, and Key all from the same vehicle. Otherwise, it looks like you would need Consult to re-register the controller IDs.


Last edited by miscrms; 04-14-2015 at 01:43 PM.
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Old 04-20-2015, 06:32 PM
foxr foxr is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

This is very interesting as I'm hoping to either A. Use a leaf to do the same thing into a fiat500 or other small car or B. get the drivetrain and build the rest using the open source controller plans on net.
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Old 04-20-2015, 06:59 PM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

I think the only real "downside" I see to this approach so far is you really need to have a number of the major components all from one car. The LBC (BMS) and VCM have a security code / transaction that must be registered with the dealer consult tool if they don't already match. The battery modules themselves could probably be from another vehicle as long as you use the LBC from the same donor as the VCM. Additionally the BCM, VCM, security dongle and key all have similar security ID registration. A missing key may be something a locksmith could help with (if they have a ~$10k state of the art multi-brand programmer), but otherwise these would also all require the dealer tool to register the new IDs.

From my perspective, this didn't seem to be a substantial downside. From what I could tell, by the time you've rounded up all the pieces from various sources you'd have easily spent in the same $5-7k range that complete salvage vehicles can be found for. And with the whole vehicle available, there might be other pricy bits in there worth using, like the AC system for instance.

Open source control would be great from a flexibility standpoint, but I would think its going to be hard to beat the robustness of the oem control system. I may very well start moving in that direction at some point, and will probably use my conversion as a test bed for some CAN snooping and experimentation, but to me it seemed to make sense to get it all working in stock configuration first. We'll see how smart an idea that was soon

Incidentally, I just won a salvage 2012 at auction for just under $7k so hopefully I can start testing this all out soon In the mean time I guess I better crack the MY 2012 service manual and make sure there aren't any substantial differences to the behaviors noted above!

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Old 04-20-2015, 07:09 PM
miscrms miscrms is offline
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Default Re: Re-using complete Leaf Drive System (w/VCM)

I did also find one more potential gotcha

I've added the DTC / failsafe info from the IBU (intelligent brake unit) to the spreadsheet linked above. The IBU seems like it does not have any failsafe modes associated with inability to communicate with any controllers other than perhaps the VCM, but C1A74 is a steering sensor malfunction DTC that does lock out regen. It may be that the steering controller has to be present in order to generate that error, in which case leaving it out should be ok. But we'll have to see about that

I'll update the first post with that info when I get the chance.

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